This undated file photo provided by the family shows Danvers High School teacher Colleen Ritzer, whose body was found behind the school on Oct. 22. / Family photo via AP

by John Bacon, USA TODAY

by John Bacon, USA TODAY

A box cutter was used to kill the 24-year-old math teacher whose body was found in the woods near her Massachusetts school, multiple media outlets were reporting Thursday.

Philip Chism, 14, is charged with murder in the death Tuesday of Colleen Ritzer, who taught at Danvers High School. Myfoxboston.com, citing an undisclosed source, was among media reporting that Chism told police he followed Ritzer into the women's restroom, punched her in the face and slashed her throat with a box cutter.

Myfoxboston reported that Chism then put Ritzer's body in a recycling bin and dragged it into the woods.

Ritzer had asked Chism to stay after school on the day she was killed because she wanted to help him with an upcoming test, a student in the class told The Boston Globe. Rania Rhaedaoui, 14, told the Globe she also was in the last-period algebra class.

"She saw him drawing during class and she just said to him, 'I didn't know you could draw,'" the freshman said. "I sit really close to him, so I could hear."

Rhaedaoui said she later heard Ritzer ask Chism to stay after school.

"She just said, 'Can you stay after with me?' He just gave a nod," she told the Globe. "There was a test coming up, and she wanted to know if he had any questions on learning equations," Rhaedaoui said.

Police had tweeted Tuesday that Chism was last seen about 6 p.m. Tuesday at the Hollywood Hits movie theater in Danvers. Theater manager Scott Przybcien told the Boston Herald that Chism saw the 4:30 p.m. screening of the Woody Allen film Blue Jasmine.

"All we know is, he bought a ticket, saw a movie and left," Przybcien told the Herald. "It was a fairly busy day. He blended right in.

"I think he just was wandering, looking for a place to hide. A movie theater is a perfect place for that. That's what we do for a living - forget about life for two hours."

Essex County District Attorney Jonathan Blodgett said police were notified at 11:20 p.m. Tuesday that Ritzer had not returned home from work and was not answering her cellphone.

Police went to the school and found blood in a school bathroom. Her body was found soon thereafter.

Investigators said in court documents that the arrest was made based on statements by the suspect, evidence from school surveillance cameras and corroborating evidence in multiple places.

Police found Chism, who was reported missing Tuesday night, walking along a road in nearby Topsfield shortly after midnight Wednesday morning.